Conventionally, a three-way valve is used for distribution or mixing of flows of fluid in a cooling system using coolant water, for example. When the three-way valve distributes a flow of fluid, the three-way valve separates fluid which has flowed therein through a single inflow port into outflow ports which extend in different two directions. At this time, the three-way valve moves a valve element in a valve chamber to adjust a ratio of flow rates of the fluid distributed into the two outflow ports.
Such technology regarding a three-way valve is known in Patent Literature 1 (JP 2001-200941 A corresponding to U.S. Pat. No. 6,289,913 B1). The three-way valve of Patent Literature 1 includes an inlet attachment portion as an inflow port, and a first outlet attachment portion and a second outlet attachment portion as two outflow ports which extend in different directions. The three-way valve separates fluid which has flowed therein from the inlet attachment portion into the first outlet attachment portion and the second outlet attachment portion, respectively.